AngularJS:如何使用指令从具有特定ng-model的所有元素中动态删除类？

angular.module('myApp', [])
  .directive('removeClass', function($document) {
    return {
      link: function(scope, element, attrs) {
        scope.$watch(attrs.ngModel, function(newValue, oldValue) {
          var elements = $document.find('[ng-model="' + attrs.ngModel + '"]');
          angular.forEach(elements, function(el) {
            angular.element(el).removeClass(attrs.removeClass);
          });
        });
      }
    };
  });

<div ng-app="myApp">
  <input type="text" ng-model="model1" remove-class="my-class">
  <input type="text" ng-model="model2" remove-class="my-class">
  <input type="text" ng-model="model3" remove-class="my-class">
</div>